Re: [RFC-v2 1/6] msix: Work-around for vhost-scsi with KVM in-kernel MSI injection

On Mon, 2012-08-13 at 21:17 +0300, Michael S. Tsirkin wrote:

On Mon, Aug 13, 2012 at 08:06:17PM +0200, Jan Kiszka wrote:

quoted

On 2012-08-13 20:03, Michael S. Tsirkin wrote:

quoted

On Mon, Aug 13, 2012 at 02:06:10PM +0200, Jan Kiszka wrote:

quoted

On 2012-08-13 10:35, Nicholas A. Bellinger wrote:

quoted

From: Nicholas Bellinger <redacted>

This is required to get past the following assert with:

commit 1523ed9e1d46b0b54540049d491475ccac7e6421
Author: Jan Kiszka [off-list ref]
Date:   Thu May 17 10:32:39 2012 -0300

    virtio/vhost: Add support for KVM in-kernel MSI injection

Cc: Stefan Hajnoczi <redacted>
Cc: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Anthony Liguori <redacted>
Signed-off-by: Nicholas Bellinger <redacted>
---
 hw/msix.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/hw/msix.c b/hw/msix.c
index 800fc32..c1e6dc3 100644
--- a/hw/msix.c
+++ b/hw/msix.c

@@ -544,6 +544,9 @@ void msix_unset_vector_notifiers(PCIDevice *dev)
 {
     int vector;
 
+    if (!dev->msix_vector_use_notifier && !dev->msix_vector_release_notifier)
+        return;
+
     assert(dev->msix_vector_use_notifier &&
            dev->msix_vector_release_notifier);
 

I think to remember pointing out that there is a bug somewhere in the
reset code which deactivates a non-active vhost instance, no?

Jan

Could not find it. Could you dig it up pls?

http://thread.gmane.org/gmane.linux.scsi.target.devel/2277/focus=2309

Jan

Ah yes. So let's not work around, need to get to the bottom of that.

Ok, so the assert being triggered in msix_unset_vector_notifiers()
appears to have been a side effect of the memory corruption bug in
virtio-scsi fixed in Patch #6, and is no longer required to start
vhost-scsi with the bugfix in place.

That said, dropping this patch for RFC-v3..